Subway is partnering with Beyond Meat to test a vegetarian twist on one of its classic sandwiches.

The Milford-based sandwich chain announced Wednesday that it will be partnering with the popular plant-based protein brand to put meatless meatballs in its marinara sub. Starting in September, almost 700 Subway restaurants will offer the “Beyond Meatball” marinara sub.

“Our guests want to feel good about what they eat and they also want to indulge in new flavors. With our new plant-based Beyond Meatball marinara sub, we are giving them the best of both worlds,” Len Van Popering, Subway’s chief brand and innovation officer, said in a news release.

The collaboration with Beyond Meat is the latest in a list of changes that Subway has implemented in recent years to revive customer interest. The Milford company is the largest fast-food company in the world by store count, with more than 21,000 restaurants in the United States alone. The chain used to have more, but several years of lagging sales led to the closure of more than 1,000 locations in recent years.

Since the start of 2018, the chain has launched a series of campaigns focused on tempting customers back into franchise locations, including a redesign of hundreds of locations. Subway announced last month that about 10,500 U.S. location would be remodeled by the end of 2020, thanks to a multi-million-dollar grant program covering about 25 percent of the redesign costs.

Subway has also been investing in sprucing up its menu since 2018, starting its partnership with a collaboration with Tastemade, a food and travel network that looks closely at consumer trends.

The partnership was initially touted as a means for Subway to develop new menu items based on customer preference.

In the last month alone, the sandwich chain announced it was using King’s Hawaiian for its bread and teaming with Halo Top to add milkshakes to the menu for the first time.

According to Beyond Meat Founder and CEO Ethan Brown, the company is hoping the partnership will last beyond September

“We’re excited to partner with Subway and are grateful that the menu team through to senior management has entrusted us as their innovation partner to deliver delicious plant-based proteins to their guests,” he said in a press release.

Beyond Meat, along with other meat-substitute brands, appear to be a rising trend. Subway is joining Dunkin’ Donuts, Burger King and other restaurant chains that are jumping onboard with a wave of new meat substitutes items.

Beyond Meat earned $67.3 million in the second quarter compared with $17.4 million during the same period last year. Roughly half of that revenue came through restaurant and food service sales.

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